Carbon dioxide (“CO2”) lasers have a variety of industrial uses, including material processing. For example, a CO2 laser can cut shapes or profiles out of materials, remove or modify surface layers of materials, and weld or sinter materials. A CO2 laser typically has a sealed resonator structure containing a laser cavity filled with a process gas. The laser cavity houses electrodes configured to couple electromagnetic energy into the process gas to excite a plasma. In general, the output power level of a CO2 laser is inversely proportional to the process gas plasma temperature; as the process gas temperature increases, the laser output declines proportionately. Thus, an effective solution for heat removal from the laser superstructure is paramount to achieving optimum laser power output. CO2 lasers typically operate at efficiencies of less than 15%, making thermal management one of the key design challenges for effective CO2 laser operation.
In some CO2 laser designs, liquid cooling schemes are employed to remove heat from the laser cavity. In a liquid cooling scheme, a heat exchanger (e.g., a refrigerated chiller) removes heat by pumping a liquid coolant through the electrodes and/or the laser superstructure. One disadvantage of liquid cooling is that it increases the complexity of a laser and the cost of ownership. Other CO2 lasers employ an air cooling scheme. In an air cooling scheme, heat from the plasma is transferred into the electrodes. The electrodes transfer heat into the outer walls of the laser superstructure, where a high-surface-area structure with forced air flow removes the heat from the resonator structure. Although air cooling is less complicated than liquid cooling, it is not as efficient. Thus, air-cooled CO2 lasers typically have a greater power output sag as their temperature tends to increase more during operation than their water-cooled counterparts. Due to these limitations, at this time the maximum output power produced by air-cooled CO2 lasers does not exceed 100 W.